LASER stands for “Light Amplification by Stimulated Emission of Radiation”.
L = Light
A = Amplification (by)
S = Stimulated
E = Emission (of)
R = Radiation
Theodore H. Maiman of the Hughes Research Laboratory, California, was the first scientist. He is the one who experimentally displayed laser by flashing light through a ruby crystal in 1960. But the basic idea behind the development of laser was given by the great scientist “Albert Einstein” in 1917.
Figure : Laser
Properties of Laser
- Laser is one of the powerful source of light with remarkable properties. These properties do not exist in the conventional light sources like incandescent light.
- One of the properties of laser that make it unique is that it can travel long distances with very little divergence whereas conventional source of light can travel very short distances.
- Another exceptional property of laser is its high degree of directionality and monochromaticity (means same colour or single wavelength). This is the reason that laser beam travel in the same phase and also the colour of laser beam remains the same throughout their journey.
- The laser beam is highly collimated and spreads very little whereas the beam of ordinary light spreads out very quickly.
- As laser light is highly collimated that on the surface of the moon, laser beam can spread out about 3Km only. Whereas if beam from a conventional light source was able to travel to the moon, its beam would have fanned out to an extent of 40, 000 km, which is much more than laser light.
- Another extraordinary feature of laser is the concentration of its energy to extremely high intensities. Intensity of the laser beam remains almost constant over long distances because the laser beam diverges to a very small extent.
- When a beam of laser with a power of a few megawatts is focus by a lens at a spot with a diameter of 1/1000th of a centimeter, the intensity of the laser beam increases to a few hundred billion watts per sq. cm. The energy becomes so high that it easily ionizes the atmospheric air to create sparks. When an intense beam is focus on unbreakable metal like diamond, even it can melt in a fraction of second.
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